Previous research suggests the extratropical atmospheric circulation responds to that sea‐surface temperature (SST) variability in the western North Pacific. However, the relative roles of oceanic and atmospheric processes in driving the SST anomalies that, in turn, seemingly influence the atmospheric circulation are unclear. Here, we exploit a simple stochastic climate model to subdivide the SST variability in the Kuroshio‐Oyashio Extension region into components forced by oceanic and atmospheric processes. We then probe the lead/lag relationships between the atmospheric circulation and both components of the SST variability. Importantly, only the oceanic‐forced SST variability is associated with robust atmospheric anomalies that lag the SSTs by 1 month. The results are consistent with the surface heat fluxes associated with atmospheric and oceanic‐forced components of the SST variability. Overall, the findings suggest that ocean dynamical processes in the western North Pacific play an important role in influencing the variability of the extratropical circulation.
Observations reveal two distinct patterns of atmospheric variability associated with wintertime variations in midlatitude sea surface temperatures (SSTs) in the North Pacific sector: 1) a pattern of atmospheric circulation anomalies that peaks 2–3 weeks prior to large SST anomalies in the western North Pacific that is consistent with “atmospheric forcing” of the SST field, and 2) a pattern that lags SST anomalies in the western North Pacific by several weeks that is consistent with the “atmospheric response” to the SST field. Here we explore analogous lead–lag relations between the atmospheric circulation and western North Pacific SST anomalies in two sets of simulations run on the NCAR Community Earth System Model version 1 (CESM1): 1) a simulation run on a fully coupled version of CESM1 and 2) a simulation forced with prescribed, time-evolving SST anomalies over the western North Pacific region. Together, the simulations support the interpretation that the observed lead–lag relationships between western North Pacific SST anomalies and the atmospheric circulation reveal the patterns of atmospheric variability that both force and respond to midlatitude SST anomalies. The results provide numerical evidence that SST variability over the western North Pacific has a demonstrable effect on the large-scale atmospheric circulation throughout the North Pacific sector.
more » « less- Award ID(s):
- 2055121
- NSF-PAR ID:
- 10367071
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of Climate
- Volume:
- 35
- Issue:
- 11
- ISSN:
- 0894-8755
- Page Range / eLocation ID:
- p. 3335-3352
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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